# ignore_handler_s

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< c‎ | error

Defined in header ``<stdlib.h>`` |  |
void ignore_handler_s( const char * restrict msg, void * restrict ptr, errno_t error ); |  | (since C11)

The function simply returns to the caller without performing any other action.

A pointer to this function can be passed to set_constraint_handler_s to establish a runtime constraints violation handler that does nothing.

  As with all bounds-checked functions, `ignore_handler_s` is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including `<stdlib.h>`.

### Parameters

msg | - | pointer to character string that describes the error
ptr | - | pointer to an implementation-defined object or a null pointer. Examples of implementation-defined objects are objects that give the name of the function that detected the violation and the line number when the violation was detected
error | - | the error about to be returned by the calling function, if it happens to be one of the functions that return errno_t

### Return value

(none)

### Notes

If `ignore_handler_s` is used as a the runtime constraints handler, the violations may be detected by examining the results of the bounds-checked function calls, which may be different for different functions (non-zero errno_t, null character written to the first byte of the output string, etc)

If `set_constraint_handler_s` is never called, the default handler is implementation-defined: it may be abort_handler_s, ignore_handler_s, or some other implementation-defined handler.

### Example

Run this code

    #define __STDC_WANT_LIB_EXT1__ 1
    #include <string.h>
    #include <stdio.h>
    #include <stdlib.h>

    int main(void)
    {
    #ifdef __STDC_LIB_EXT1__
        char dst[2];
        set_constraint_handler_s(ignore_handler_s);
        int r = strcpy_s(dst, sizeof dst, "Too long!");
        printf("dst = \"%s\", r = %d\n", dst, r);
        set_constraint_handler_s(abort_handler_s);
        r = strcpy_s(dst, sizeof dst, "Too long!");
        printf("dst = \"%s\", r = %d\n", dst, r);
    #endif
    }

Possible output:

    dst = "", r = 22
    abort_handler_s was called in response to a runtime-constraint violation.

    The runtime-constraint violation was caused by the following expression in strcpy_s:
    (s1max <= (s2_len=strnlen_s(s2, s1max)) ) (in string_s.c:62)

    Note to end users: This program was terminated as a result
    of a bug present in the software. Please reach out to your
    software's vendor to get more help.
    Aborted

### References

- C11 standard (ISO/IEC 9899:2011):

  - K.3.6.1.3 The ignore_handler_s function (p: 606)

### See also

abort_handler_s (C11) | abort callback for the bounds-checked functions (function)
set_constraint_handler_s (C11) | set the error callback for bounds-checked functions (function)

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